Overload cutout for stoker motors



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75N TDR vv. e. Moons- Patented Nov. 26, 1935 UNITED STATES PATENT OFFICE OVERLOAD CUTOUTFOR STOKER MOTORS Wilfred E. Moore, Cleveland, hio

Application December 14, 1931, Serial No. 581,044 Renewed April 29, 1935 s claims. (o1. 19a-15o) This invention relates generally to coal burning stokers, and particularly to an overload cut-out for stoker motors.

The main object of this invention is to provide a means for automatically stopping the stoker motor when it is objectionably overloaded, thereby protecting the mechanism of the Stoker and the motor itself from injury, and at the same time preventing air from being fed to a fuel bed with- 0 out fuel and permitting the fuel to burn down to the tuyres and finally cause the destruction thereof. A

These, and other objects, `will become more apparent from the specification following as illus- L5 trated in the accompanying drawing, in which:

Fig. l is a perspective view of a Stoker with the tuyre section omitted and with a portion of the fuel duct broken away in section.

Fig. 2 is a section taken along the line 2-2 in Z0 Fig. 1 and showing the cut-out in a motor operating position.

de... Fig. 3 is a view similar to Fig. 2 but showing the cut-out in an over-load position.

Fig. 4 is a perspective view of the cylindrical shell of my device.

Fig. 5 is a perspective view of the plunger.

Fig. 6 is a transverse section along the line 6-6 in Fig. 2.

Similar numbers of reference refer to similar parts throughout the several views.

Referring in detail to the drawing, in order to illustrate this invention there is shown the usual form of hopper I0 from which fuel is fed through a fuel duct into a retort (not shown) by a fuel feed screw I2.

I3, fan casing I4 and airduct |5 are also illustrated, as well as the gear case I6.

Referring particularly to my invention attention is drawn to the cap I1 which projects from the gear case I6 and within which is contained the operating mechanism of the motor cut-out device.

The fuel feed screw |2 is driven from the shaft I8 through the gearing in the case I6. The end I9 of the shaft IB is mounted within the gear 20 and is driven thereby through the shear pin 2| which passes through thehub 22 and the shaft end I9. The hub 22 journals in the bushing 23 whose threaded end 24 carries the cap I1. It isdesirable to provide a gasket 25 between the end of the cap |1 and the boss 26 in the gear case I6. The pin 2| is a loose fit in the holes provided therefor and it is adapted to shear when the load on the feed screw I2 becomes excessive. If the motor |3 is permitted to continue to operate after The usual operating motor the pin 2| has sheared it is obvious that the fan Will supply air to the fuel bed which will not be renewed, owing to the fact that the feed screw I2 has stopped rotating and the fire will eventually burn down to the tuyres, which of course is very detrimental to these elements and frequently occasions the complete renewal thereof. This is due to the fact that lthe shear pin has been severed caused by the entrance of a foreign substance in the fuel, and the attendant is not aware of the l0 fact that the fuel feed has stopped and air is therefore supplied to the lire while the tuyres are not protected by the incoming green coal.

In order that the motor I3 will shut down the instant the pin 2| shears there is provided a cyl5 lindrical shell 21 which slips easily over the end of the hub 22 before the pin 2| is put into place. The shell 21 is provided with holes 28 which register with the holes 29 in the hub 22 through which the pin 2| passes. 20

Between the holes 28 are formed the slots 30 which receive the spring wire retaining ring 3| whichprevents the pin 2| from coming out of itsk opening, and the pin 2| prevents the shell 21 from slipping off of the hub 22 or rotating with rela- 25 tion thereto. AThe shell 21 has also a pair of diametrically opposed inturned ears 32, which will be referred to as stops.

The shaft end I9 has its tip 33 reduced in diameter and squaredand has slidably mounted 30 thereon a cylindrical plunger 34 having a closed end 35 and an open end 36, through which open end projectsoutwardly the lugs 31. llhe plunger 34 is provided with a square recess 33--A which slidably receives the square end 33 of the shaft I9. 35 The shaft end |9is provided with a recess 38 for a spring 39 which urges the plunger 34 outwardly.

In the end 40 of the cap I1 is an insulator bushing 4| in .which are mounted the contacts 42 and 43. The contacts 42 and 43 are joined by the 40 wires 44 to the electrically operated switch 45 which normally closes a gap in the motor circuit 46, but which, when energized, opens this gap and causes the motor I3 to cease operating. It is preferable to operate the switch 45 from the 45 transformer 41.

The operation of the device is as follows: Assuming that the stoker is operating and the parts are in the position shown in Fig. 2 and the feed screw |2 becomes overloaded causingthe pin 2| 50 to`shear (as shown in Fig. 3), the lugs 31 will disengage the ears 32 and the plunger 34 will move outwardly coming in to engagement with thel two contact points 42 .and 43 thereby energizing the switch 45 and stopping the motor. Ob- 55 viously, the same action may cause a visiblev or audible signal to be given, although the outstanding feature of this device is to protect the stoker from unnecessary and possibly destructive operation.

I claim: f

l. An overload cut-out for stoker motors consisting of a drive gear having a hub on one side thereof, a feed screw shaft within said hub, a shell surrounding said hub having a pair of inturned stops on the outer end thereof, a shear pin passing through said shell hub and shaft, a spring-urged plunger held in a retracted position by said stops, and a pair of contacts adapted to be bridged by a releasing movement of said plunger occasioned by a shearing of said pin and a subsequent unlatching of said plunger.

2. an overload cut-out for Stoker motors consisting of a cylindrical band having a pair of inturned stops on one side thereof and having a pair of diametrically opposite holes adapted to register with the shear pin holes of a feed screw drive, a plunger slidably mounted on the end of the feed screw shaft and adapted to be rotatably driven thereby, said plunger having out-turned lugs normally engaging said stops when said shear pin is intact.

3. An overload cut-out for stoker motors consisting of a cylindrical band having diametrically opposite pin holes formed therein through which the shear pin of a feed screw worm can pass, a slidable plunger mounted on the end of said feed screw and rotatably driven thereby, spring means for urging said plunger outwardly, a latch between said plunger and band whereby a relative plunger shall along the axis of said feed worm, and a cap for housing said band and plunger including a pair of contacts in the path of said plunger adapted to be bridged by the outward movement thereof.

4. A device or the class described comprising a round driven shaft having a square end, a plunger slidably mounted on said squared end, a spring between said plunger and squared end for urging same apart, said plunger having a pair of outturned lugs extending therefrom, a driving element rotatably mounted on said shear pin forming a driving connection between said round shaft and driving element, a pair o1' ears carried by said driving element arranged to engage said lugs for the purpose of holding said plunger in a retracted position when said shear pin is intact, and a pair of spaced contacts in the path of said slidable plunger capable of being bridged thereby when said pin is sheared by an over-load and said lugs are turned away from engagement with said ears.

5. The substance of claim 2 together with a retaining ring encircling said shell, said shell having grooves formed therein between its pin holes for the reception of said retaining ring.

6. 'I'he combination of a driving member and a driven member, a shearing connection between said members, a cap secured to said driving member, a member rotatively secured to said driven member, a connection between said cap and said last named member whereby upon shearing of said shearing member said last named member move endwise for operating a switch.

7. In combination, a shaft, a coaxial member, a motor, a working part, a shear pin connecting said member and said shaft so thatthe motor drives the working part, two cooperating devices extending beyond the free end of the shaft and having relative axial axial movement of said devices.

8. In a stoker, a shaft, a coaxial sleeve, an electric motor, a feed screw, a shear pin connecting the sleeve and shaft so that the motor drives the feed screw, two cooperating devices extending beyond the'free ends of the shaft and sleeve and having relative axial movement, one of said demovement of said devices.

9. In combination, four elements rotating about a single axis including a driving member, a driven member and two electric current controlling devices, one of said devices having axial movement, a shear pin to cause the and means to cause one of the two devices to move axially upon relative rotation of the two members when the pin is sheared.

four elements to rotate l WILFRED E. MOORE. 50 

